Let’s get this straight from the beginning: if you start writing a novel, plan ahead to finish it. The true writer always finishes what he begins. Don’t let boredom or lazyness to slow you down.
Writing a novel is all about a right momentum. Every time you stop to make a revision, you loose it. Don't stop to revise a scene somewhere in the middle of a novel, to look up a word, or even change the plot. It's better to leave notes in draft. For example, highlight empty spaces or fill text with checkmarks. In such way, you will know where to come back later.
It is important to realize that the first draft doesn't need to be perfect. There is also no need to finish it in record time. This is just the first draft, so it can and even should look like a warzone. Don’t be too harsh and strict, the main thing is that you did it, and now can move forward.
A true author should find joy in writing his/her first draft without caring too much about its content. It is okay to get messy sometimes. Have fun and enjoy what you do. Yes, it may look like you are just messing it up at first, but later you’ll find treasure amongst it all.
Don't be afraid to take risks. Always try new things. This may refer to playing with language or killing an important character. Experiment. You will get a chance to revise in the subsequent drafts. Some parts will be deleted, but those that stay will feel priceless.
As it was already mentioned, writing is about making the words, editing is about making them sound right. Develop your writing, make your novel grow up. Do this with the help of rewriting. Rewrite. And rewrite. And rewrite. Do it as many times as needed till it is what it should be.
Unlike in other jobs, where people have one chance to succeed, the novelist has many chances to correct mistakes. He can keep adding, rewriting, fixing, changing up until he's completely satisfied.
Every writer has to stop sometime. Otherwise, it may get worse. They say the perfect is worst enemy of the good. A novelist should continue writing till it’s good, but not till it is perfect. There's no way to define what perfect is, therefore, just do it good and let other people improve it.